Hi everyone this is my first post after buying my x350 in 2015 with 140,000 miles.
I recently had my throttle body changed at a independent jag shop because it started to fail. I've attached the codes I had prior to any work being done as well.
After dropping my car of at the shop the mechanic calls me and says " you need a new timing chain and tensioners because your car is making a noise when you start it up for a second then goes away. I explained to him that the car always made the noise since I brought it 2 years ago. He says I definitely need a throttle body also to solve the limp mode issue. The mechanic replaced the throttle body front height sensor and rear sway bar links. I payed drove the car about 5 miles stopped at a red light stepped on the gas once the light was green now the car goes into limp mode after throttle body replacement. I have the car towed back to the same shop now the mechanic is saying the timing belt is causing the limp mode. My question is could the timing chain cause the throttle body to fault. The noise I hear during start up sound more like a VVT Unit issue based of my own research recently.

 

Will follow this thread with interest.

 

I've deleted your duplicate of this post from General Tech Help. Please do NOT multiple post the same question across forums.

Graham

 

Check your TPS and MAF. But first, double check your battery (12.45+ VDC after sitting overnight). Replace as required

Erase codes and drive a few miles

If repeat codes, check for vacuum hose leaks/routing

Hope this helps

 

The 4.2 engine do not commonly have tensioner or chain issues. The codes do not point to internal engine problems.

 

Thank you all for the advise!! I'll updated soon..

 

If I remember correctly, that if just the tps is changed, a recalibration is required. I'm probably all mixed up. I just remember a procedure from an old post that required that the throttle position be recalibrated. Can anyone chime in and confirm or correct me? I believe it required something like - throttle all the way down in the multi-step procedure. Seems like Ralph's mech is missing something. Everything shown points to a throttle issue. Hence the work recently completed.
Lean code is an easy one, and should not shut the car down, unless it's a gaping hole. But we have seen a HUGE hole in the intake elbow in a recent post, and the car still ran. Leak only in bank 1. Need to see fuel trims, and other data to pinpoint causes. The mech should have these as he couldn't/shouldn't recommend parts solely on dts codes. Give us more data so we can help.
When did we get timing belts? Somethings fishy.

 

Mark in Maine Thanks! I'll get more information

 

Those codes look what you could easily get from a failing battery or bad power or a chafed harness. I see NOTHING to suggest the timing chain or even the TB.

Can you not either DIY or find a better shop?

 

What messages are you getting when it goes into limp mode? Did you try starting it 5 times in a row to get it out of limp mode?

I had mine go into limp mode once and I was convinced it was due to rain and moisture. Put dialectric grease on the outside of the plug to the throttle body and it's been thousands of miles since and never saw it again. I got this advice from the s type r forum if I recall which has the throttle body positioned similiar to the XJR.

 

The messages I get are NO DSC, Parking Brake Fault and Engine System Fault along with yellow and red warning dash lights. The mechanic advise to day that he did find a shorted wire issue that may have contributed to my issue but also said that he has to recalibrate my air suspension now.

 

The messages I get are NO DSC, Parking Brake Fault and Engine System Fault along with yellow and red warning dash lights. The mechanic advise today that he did find a shorted wire issue that may have contributed to my issue but also said that he has to recalibrate my air suspension now.

 

Please forgive me for duplicates I'm using my phones browser to respond. Is an application available for this forum.

 

That definitely sounds like the old Throttle Position Sensor malfunction. In the old days when these cars were still fairly new, we had to get entirely new throttle bodies and they were not cheap. A new sensor should do the trick.

 

UPDATE: Aftet another week the independent jag shop finally comes to the conclusion that they installed a bad TPS and throttle body. Now they are going to replace it again. Mean while I've located a new Jag shop with a better reputation. It's a lot further away but, I'm going to take the trip if all goes well for an inspection of the work...

 

might be time to take this cat to the dealer. Picked it up today With no changes. Everything my car was doing it still does. Mechanic seems to be playing process of elimination. I'll update with the dealers diagnosis. Mechanic is suggesting hat I drive with the AC off to see what happens

 

Find another mechanic hes full of it. I would check the electrical connector on the throttle body cause theyre plasic and fail all the time. Mine on mine is down to no connector left and tight pins holding it on(i know on my list of stuff to do) any electrical drop out on these circuits will go into limp home. The chain tensioners and guides on the 4.2 are pretty damn robust. While you defintly have wear(im at 150k too) that is not your issue with restricted performnce. That is where i would start but more test needs to be done, and chacks made. Imo he is guessing and not experienced with jaguars.

 

Anyone can throw $ at a car until enough parts fixes it. The main issue is that it's not the mechanics money. Brutal is dead on. Find a real mechanic.

 

Thanks guys I'm going to a new mechanic I'll update once this problem is fixed.

 

No one in your area knows of a good mechanic, or a reputable shop???